 |
|
| SCIENCE & TECHNOLOGY |
|
|
|
Reassessing Chernobyl
Fungi fight malaria
New species of catfish
Sperms, eggs from human embryo
Propane fuel cell
|
|
|
Reassessing Chernobyl
On April 26, 2005, the United Nations Development Programme (UNDP) reported that the residents in the affected areas still lack the information needed to lead healthy and productive lives. “Misconceptions and myths about radiation prevail, promoting a paralysing fatalism among residents about their own health”. In spite of concerted efforts by international organisations, and the mass media over the past 19 years, residents are confused about the impact of radiation on their health and surroundings. They tend to attribute a wide variety of medical complaints to Chernobyl; but neglect the role of personal behaviour in reducing risk and maintaining health. The agency noted that this applies not only to radiation risks, which are actually quite low, but also to areas in which personal behaviour is decisive, such as, diet and misuse of alcohol and tobacco. Immediately after the accident, media reports reflected universal public hysteria Dr Roger Bate, visiting fellow of the American Enterprise Institute, noted that the Daily Mail filled half its front page with the words “2000 DEAD”. “The New York Post claimed that 15,000 bodies had been bulldozed into nuclear waste pits” he wrote in the National review online. Broadcasting agencies, newspapers and the Ukrainian Ministry of Health quoted death tolls varying from 15,000 to 125,000. The United Nations Scientific Committee on the Effects of Atomic radiation (UNSCEAR), the specialist agency set up in 1955 by the United Nations to evaluate sources and effects of ionising radiation reported that 31 power plant employees and firemen died within a few days or weeks. Of these, 28 deaths were due to acute radiation exposure. Additionally, as on 1998, 11 out of the 134 members of the reactor staff and emergency workers who showed signs of acute radiation sickness died due to many reasons. The number of deaths was small in comparison with other industrial catastrophes. Except some increase in thyroid cancers among children, UNSCEAR did not find any evidence of increase in overall cancer incidence or mortality or non-cancerous diseases attributable to radiation exposures. Dr Zbigniew Jaworowski, former Chairman, UNSCEAR, found that the pattern of increase in thyroid cancers “was not in agreement with what we know about radiation-induced thyroid cancers”. He cautioned that the increase in incidence should be viewed against the presence of occult cancers ranging from 5 per cent to 35 per cent among populations in many countries. These do not present adverse clinical effects. Over-enthusiastic screening must have led to the discovery of some occult cancers. There has been no statistical increase in deformities in babies. Dr Bate reported that the exhibitions of photographs of deformed victims, which raised millions of dollars for pressure groups and charities, have been exposed as fraudulent. The risk of leukemia does not appear to be elevated, not even among the workers engaged in the recovery operations. The jury is still out on this issue. The accident at Chernobyl served as a wake up call for the nuclear community. They started paying more attention to emergency planning measures. Radio-phobia caused incalculable psychological damage. —
Dr K.S. Parthasarathy is a former Secretary of the Atomic Energy |
|
Certain fungi not only kill mosquitoes but also can reduce the likelihood of them transmitting malaria before they die, according to UK-based researchers.
Spraying walls or cloths with spores of a fungus that kills mosquitoes could greatly reduce malaria transmission, according to two studies published in the recent issue of Science. Researchers led by Matt Thomas exposed Anopheles stephensi mosquitoes to the fungi and they found that the mosquitoes were 80 times less likely to transmit malaria. The mosquito transmits malaria to humans but in this study carried a form of malaria that infects rodents, it said. The researchers assessed eight strains of two fungal species: Beauveria bassiana and Metarhizium anisopliae. The fungi kill malarial mosquitoes before they can transmit the parasite. The researchers sprayed cardboard pots with fungal spores suspended in oil, then 24 hours later introduced mosquitoes that had taken a blood meal and left them for two weeks, the report said. In six of the eight tests, more than 80 per cent of the mosquitoes died. Death is not always quick, but it does not need to be, the researchers said. Mosquitoes cannot transmit malaria until about two weeks after picking up the malaria parasites with a blood meal. The fungus also affects mosquitoes’ ability to feed, making them less likely to spread malaria.
— PTI |
|
New species of catfish Mexican and US researchers say they believe an ancient-looking, rarely seen fish in a Mexican river represents a new species of catfish and an entire new taxonomic family. It would be only the third new family of fish found in the last 60 years, and could offer scientists a view into the distant past, a Mexican scientist said on Wednesday. The new species was dubbed Lacantunia enigmatica, of the family Lacantuniidae, in an article published in the online scientific journal Zootaxa. The names are derived from the fish’s habitat in the Lacantun river of southern Chiapas state, a tributary of the Usumacinta river, which marks the boundary between Mexico and Guatemala. “It’s unusual to find a new family,” said biologist Maria del Rocio Rodiles of Mexico’s Colegio de la Frontera Sur, who began finding examples of the rare fish in the mid to late 1990s. “It’s also unusual to find a new species of catfish of this size.” The Lacantunia enigmatica, “enigmatic” because scientists are not sure of its habits or its origins, is a flat-sided, thick-tailed fish that grows to about 1 1/2 feet (1/2 meter) in length. “This fish has ancestral characteristics. It is not like a modern catfish,” said Rodiles, who at first was not sure of the significance of the find, and consulted with researchers from the University of Texas at Austin and the Academy of Natural Sciences of Philadelphia. — AP
|
|
|
Sperms, eggs from human embryo Scientists in Britain have shown that stem cells extracted from human embryos can develop in the laboratory into the early forms of cells that become eggs or sperm, raising the possibility that one day eggs and sperm needed for infertility treatment could be grown in a dish. Preliminary experiments also suggest that scientists may eventually be able to use the technique to create a supply of eggs for cloning. But the more immediate benefit of the work could be a better understanding of why some men and women do not create their own sperm or eggs and whether toxic chemicals in the environment may play a role, one of the researchers said at the annual conference of the European Society of Human Reproduction and Embryology. The findings were presented in Copenhagen. “It may allow us to investigate the very earliest processes of how a human (ovary and testis) develops,” said Harry More, a professor of reproductive and developmental medicine at Sheffield University in England. Many scientists believe that chemical pollutants, such as pesticides, that mimic the action of hormones, might interfere with human development at the stage where eggs and sperm — called grem cells — are forming and that this disruption may cause birth abnormalities, infertility and possibly cancer. “By developing suitable tests with embryonic stem cells as they differentiate into germ cells we can investigate the action of these chemicals in the laboratory,” Moore said. — AP
|
|
|
Portable electronics such as laptops and MP3 players could soon run on miniature fuel cells that consume propane, the same fuel used in gas barbecues. In search of longer-lasting alternatives to conventional batteries, a team of researchers has developed just such a device. “A propane-driven fuel cell could be the same size as a lithium battery but last 10 times longer,” says Paul Ronney of the University of Southern California in Los Angeles. Other groups have previously developed fuel cells for portable electronics. However, most of these run on methanol. Propane and other large hydrocarbons are more desirable because their larger molecules pack more energy and can be easily stored as liquids rather than as pressurised gases. A small cartridge of liquid propane under moderate pressure could feed a fuel cell for days. Most batteries require recharging after only several hours of continuous use. In the June 9 Nature, Ronney, Sossina Haile of the California Institute of Technology in Pasadena, and Scott Barnett of Northwestern University in Evanston, Ill., describe their dime-size fuel cells. A primary focus of their work was to design a fuel cell that could heat itself up to the 500° to 600°C required to convert propane into electricity.
|
|
|
THIS UNIVERSE
Q. Will the oceans ever become “extinct” due to deposition of decayed particles on the seabed? A. Over long (or “geological”) time scales, the oceans and mountains are being continuously transformed. For example, a few hundred million years ago, the landmass of India was in the Southern Hemisphere. There existed a big ocean where most of India is now located. There were no Himalayas to our North. This awesome mountain range was created slowly when India collided with the Asian continent. This collision is still in progress; India is still moving North-North-East at a rate of about 5 cm a year, with the land mass burrowing under China. (In the last million years, the displacement would therefore have been more than 50 kilometers; the birthplaces of Gods and early humans in our land must have moved through a distance of this order or more!). All over the world, sea fossils are found on tops of high mountains, showing that nothing is permanent on these time scales. The earth is continuously transforming. Large oceans have mid-ocean ridges where matter comes out from deep inside the earth as hot lava, sometimes making islands that rise tall — or not so tall — above the sea surface. Continuing eruptions spread the outcoming matter that is transported along the ocean bottom to edges of continents where it is subducted back into the earth’s mantle. Some of such subduction zones lie along the West Coast of North America and along the eastern edge of Asia. There is continuous change. What will happen in millions of years can only be surmised. Dead matter arising out of living things does change the morphology of the oceans. For example, many coral islands and reefs are nothing but accumulations of coral skeletons; these organisms grow at relatively shallow depths so they can utilise the penetrating sunlight. Coral mountains sticking high above the sea surface cannot exist because coral needs seawater and sunlight together. Though qualitatively significant, this phenomenon also rides on the much larger basic elements of the drama that keeps altering the surface of the earth. If there were no volcanoes on the sea floor, there would not be any isolated hills reaching out from deep ocean depths around which we have so many beautiful coral reefs — no Lakshdeep, Mali, Andamans or
Hawaii. Q. Our eyes cannot detect ultraviolet radiation, a capability found in bees. How would the sun appear to bees? A. Bees also see in visible light. Their vision towards the red end of the spectrum is poor, to the extent that what appears red to humans would be black for them. They certainly can see much further beyond the violet, towards shorter wavelengths. That they can see in the “visible” light and also differentiate between different colours has been established. The sun would be visible very well, but the hues would be different. The ability to detect ultraviolet must confer some biological or evolutionary advantage. I do not know whether the bees derive aesthetic pleasure from the abundance of illumination during the day. If they do have a name for the light that comes through scattering from air molecules, something that gives us our blue skies, their sky would be rather “ultravioletly” blue! On the other hand their relative insensitivity to red would deprive them of orange sunsets or the red globe of the setting sun. In addition, the bees do share with many birds a faculty that we do not have. This is the ability to detect the plane of polarisation of skylight. Polarisation is also the result of light scattering and its degree and direction depend on the angle between direction of seeing with respect to the direction of the sun. Thus the direction of the sun can be determined even during a cloudy day, if a small pocket of the blue sky is still visible; clearly, this capability would be extremely useful for navigation. As mentioned above, it is definite that bees are quite sensitive to ordinary light. When they return to the hive after detecting a source of food, they communicate the information about the find to other bees through an intricate dance, wherein the direction of the find is indicated with respect to the direction of the sun at that time. If the hive is darkened and then artificially illuminated with a light bulb, the position of the bulb is taken to be the direction of the sun, and the dance is modified accordingly!
|
| HOME PAGE |
Holographic movies In a small research laboratory at UT Southwestern Medical Centre, a grainy, red movie of circling fighter jets emerges from a table-top black box, while nearby, a video of a rotating human heart hangs suspended in a tank of gooey gel. These images - the first true, three— dimensional, holographic movies — are the brainchild of Dr Harold “Skip” Garner, professor of biochemistry and internal medicine at UT Southwestern. While such movies will not be coming soon to a theatre near you, they have earned Dr Garner and his “holographic television” a spot on Popular Science magazine’s list of the top five “great ideas for the future,” featured in the June 2005 issue. Plant sacrifices Researchers recently discovered a gene essential to one of the plant kingdom’s key immune responses—programmed cell death (PCD). Plants use PCD to create a protective zone of dead cells around the infection site to prevent the invading pathogen from spreading. But how the plants keep from killing themselves after they turn on the cell-suicide process was a mystery. Now, in the May 20 issue of the journal Cell, Yale University’s Savithramma Dinesh Kumar and his colleagues report finding a gene that normally propagates a “pro-survival” signal in plant tissue. Mapping aroma Researchers decades ago mapped out the brain’s sense of touch, with patches of neurons corresponding to body parts, such as a hand, a lip, or the torso. A new study suggests that the sense of smell may have its own brain atlas. The finding adds to a growing body of research on smell, which scientists haven’t studied as much as touch, hearing, or sight. Last year, Linda Buck of the Fred Hutchinson Cancer Research Center in Seattle and Richard Axel of Columbia University shared the Nobel Prize in Physiology or Medicine for their work in deciphering the mechanisms behind smell. |
On April 26, 1986, a severe nuclear accident occurred at the Chernobyl nuclear power station. Now we must have a re-assessment of the impact of the accident objectively, dispassionately and scientifically. The accident had enormous psychological impact primarily because of large scale evacuation of population from the affected areas.
